Drill bit



J. F. sHAw 2,201,379

DRILL BIT Filed June 2, 1939 2 Sheets-Sheet 1 I, Qgfxr v J. F. SHAW May21, 1940.

DRILL BIT Filed June 2, 1939 2 Sheets-Sheet 2 Patented May21 1940 PATENTOFFICE DRILL BI'I' John F. Shaw, Los Angeles, Calif.I assignor to ReedRoller Bit Company, Houston, 'lex., a

corporation of Texas Application June 2, 1939, Serial N0. 276,968 '1Claims. (Cl. 255-571) This invention relates to drill bits, and hasparticular reference to bits of the roller type, wherein roller cuttersare rotatablymounted on the bit head and are provided with-cutter teethwhich dig into the formation as the cutters roll thereupon.

'The general object of this invention is to provide a novel andadvantageous structure which may be more readily assembled and whichwill provide a more effective and durable drill than those in useheretofore. 1

In the type of drilling bit known as a cross roller bit there arecustomarily provided a pair of side cutters adapted to cut at the sidesof the bottom of the hole and located in positions which aresubstantially diametrically opposite each other with respect to the bithead. Between these two cutters and extending. transversely with respectto a line drawn between them there is ordinarily a cross roller cutterpin on which are mounted a plurality of cross roller cutters adapted tocut the central portion of the bottom of the hole. These cross rollerpins are normally disposed on a plane substantially at right angles to'the axis of rotation of the bit and when the bit is in vertical positionthe cutter pins and cross roller cutters mounted thereon will have theiraxes disposed substantially horizontally and in alignment with eachother. v 9 In the usual type of bit just described the axial extent ofthe side cutters is limited by the presence between the side cutters ofthe cross roller cutters. Considerable difficulty has been experiencedwith the bearings of the side cutters be- 3 cause of this necessarilylimited axial extent of the side cutters. Specifically, it has beenproposed that the side cutters be provided with radial bearings of thefriction type in a position spaced inwardly from the usual anti-frictionbearings.

It is an object of this invention to provide a structure of the generaltype set forth in which there will be a greater'amount of room for .theside roller cutters and bearings therefor. More specifically, it is anobject of this invention to provide a structure in which there will be agreater amount of room than in the usual construction for a frictionbearing such as above described. 1 v

' In addition to the foregoing, it is an object of this invention toprovide a structure in which the outer supports for the cross rollercutter pins will be stronger andmore durable than in previousconstructions.

Another object of this invention is to provide a drill bit structure inwhich the cutters and their bearings and supporting means may beassembled and secured together as a unit, after which they may behandledas a unit and assembled with respect to the body of the drill. 5

In the drawings: Fig. 1 is a vertical cross section illustrating a bitconstructed in accordance with this invention.

Fig. 2 is a partial vertical cross section taken 1 substantially atright angles to Fig. 1 and showing the structure of the side cuttermounting of the bit illustrated in Fig. 1.

Fig. 3 is a view showing the bit head before the cutter and bearingassembly has been se- 15 cured thereto.

Fig. 4 is a view showing the cutter and bearhing dassembly prior tomounting upon the bit Referring now more in detail to the drawings, 20the numeral i designates the bit body and the numeral 2 the threadedshank thereof by which it is connected to the lower end of the drillstem. Extending downwardly from each of the four sides of this bodymember are arms, two of which 25 are designated by the numeral 3 and theother two by the numeral 4. Each of the arms 3 and 4 is provided with aflat outer surface and with an inclined shoulder at the upper endthereof for the purpose of receiving supporting arms to an be welded orotherwise secured thereto as will be presently described.

The cutter and bearing assembly which is i1- lustrated in side elevationin Fig. 4 consists of a pair of cross roller cutters 5 and 6 and a pairof side roller cutters I mounted upon suitable bearing supports adaptedto be connected to the head I. The bearings for the cross roller cuttersconsist of cutter pins or shafts 8 and 9, respectively, the cutter pin8.being formed in this 40 instance integral with an upstanding-arm Illand the cutter pin 9-being formed with a similar arm ll. These pins are,of course, straight throughout their length and extend downwardly andinwardly as clearly illustrated in Fig. 1 and their inner ends aredisposed in an opening'in a bridge member I! which extends transverselyof the head and substantially at right angles to a line between the armsto and H. The ends of the shafts 8 and 9 may be welded together withinthe opening in the bridge as shown at i3, or they may be otherwise heldin this opening by anysuitable means. The cross roller cutters 5 and 6are of such length or extent as to traverse substantially'the entirearea of the bottom of a hole within the pathof said side cutters.

The opposite ends of the bridge are provided with suitable spindles forthe reception of the side cutters 7. These spindles have axes extendingdownwardly and inwardly withrespect to each other, and it will readilybe observed that there will be a greater spaceavailable longitudinallyof these axes by virtue of the fact that the cross cutter pins" extenddownwardly and inwardly, than there would be if these cutter pinsextended substantially horizontally, in the usual manner. It is,therefore, possible to make these spindles longer by virtue of thepresent construction.

The shaftsB and 9 which support the cutters 5 and 6, respectively, areeach formed in the usual -manner with races for roller bearings it and1-5 I adapted to take the radial load from these cutters respectively,and with a race for a ball hearing [6 adapted to take the outward endthrust I from these cutters;

The spindles for the side cutters l are each provided with acircumferential groove ll adapted to receive ball thrust bearings 68 andwith a roller race IQ of reduced diameter to receive the roller bearings20. The ball bearings l8 fit the groove 2| forming a raceway in theinterior of the cutter l and 'are adapted when in place to take the endthrust of this cutter. The

outer ends of the spindles just described extend beyond the side cutter1 and areadapted to be received within openings in the side supportingarms 22 which extend upwardly therefrom. These side supporting arms areadapted to be welded as at 23 to the outer ends of the spindlesrespectively. Each of the side supportin arms is also providedwith anopening adapted to receive ,a dowel pin 24 which in turn will registerwith an opening in one of the arms 3 of the bit head when the bearingassembly occupies the proper position with respect to the bit head.

By virtue of the'additional space made availis shown in the presentexample in the form of a friction bearing, the cutter being formed witha part 28 inwardly of the race 2| adapted to bear directly upon afriction bearing surface 29 formed on the spindle. This of courseprovides a more sturdy bearing structure for the side cutters and onebetter capable of taking the tremendous radial load imposed uponthesecutters in operation.

In addition to the above, the inclination of the cross roller cutterpins makes it possible to use arms I0 and H which are of greater crosssection area above the point where the cutter pins are joined theretothan would be the case if these cutter pins were horizontal. That is,when the cutter pins are inclined as shown in Fig. 1, the arms [0 and IIjust above the outer ends of these cutter pins may be made with greaterradial dimensions than if these pins were horizontal, withoutinterfering with the action of the cutters.

This oi. course produces a much stronger and sturdier support for thecross cutter pins and a makes possible a more durable bit construction.

a to temporarily hold this assembly in place and these dowels welded inas shown at 25. The arms I0, I I and 22 may then be welded to the bithead as shown at 26 and 2-1 respectively, after which the bit is readyfor operation.

It will readily be seen from the foregoing that a means has beenprovided whereby the cross roller cutters of a roller bit may bedisposed so as to provide more room for the side cutters thereof andmake possible a more satisfactory bearing for the side cutters. At thesame time, there has been made possible a morerugged support structurefor the cross roller cutters. In addition, a structure has beendisclosed in which it is possible for the various cutter and bearing hasthus been illustrated which is capable of accomplishing all of theobjects and advantages sought by this invention.

Having described my invention, I claim:

1. In a roller bit, a pair of side cutters adapted to cut at the sidesand bottom of a hole, a pair of cross-cutter bearing pins, eachextending downwardly and inwardly toward the center. of the bit, andbeing straight throughout its entire length, and cross roller cuttersmounted on said bearing pins, said cross roller cutters being of suchextent as to traverse substantially the entire area of the bottom of ahole within the path of said side cutters. i

2. In a roller bit, a pair of side cutters adapted to cut at the sidesand bottom of a hole and each havinga relatively long inwardly extendingbearing portion, a pair of cross roller cutters extende ing transverselyof the bit, a pair of substan-' tially straight shafts on which saidroller cutters are mounted, said shafts extending inwardly anddownwardly with respect to the axis of rotation of said bit to clearsaid relatively long bearing portions, said pair of roller cutters beingof such length as to alone traverse substantially the entire area of thebottom of a hole within the path of said side cutters.

3. In a roller bit, a pair of side cutters adapted to cut at the sidesand bottom of a hole and each having an anti-friction radial bearingadjacent its outer end, a thrust bearing intermediate its ends, and africtionradial bearing adjacent its inner end, and a pair of crossroller cutters extending transversely of said bit and each ha ing anaxis extending inwardly and downwardly with respect tothe axis ofrotation of said bit to clear said friction radial bearings.

4. In a roller bit, .a pair of sidecutters adapted to cut at the sidesand bottom of a hole and each having a relatively long inwardlyextending bearing portion and a pair of cross roller cutters extendingtransversely of said bit and each having an axis extending inwardly anddownwardly with respect to the axis of rotation of said bit to clearsaid relatively long bearing portions; and a bridge member bridging thespace between said side cutters and extending between said cross rollercutters to form a support for the inner ends of said cross rollercutters.

5. In a roller bit, a pair of side cutters adapted to cut at the sidesand bottom of a hole and each having an anti-friction radial bearingadjacent its outer end, a thrust bearing intermediate its ends, and afriction radial bearing adjacent its inner end, a pair of cross rollercutters extending transversely of said bit and each having an axisextending inwardly and downwardly with respect to the axis of rotationof said bit to clear said friction radial bearings, and a bridgeextending between the inner ends of said side cutters and between saidcross roller cutters and forming a support'for the inner ends of saidcross roller cutters.

6. In a roller bit, a pair of side cutters adapted to cut at the sidesand bottom of a hole, and a pair of cross roller cutters extendingtransversely of said bit and each having an'axis'extending inwardly anddownwardly with respect to the axis of rotation of said bit, crosscutter bearing pins extending through said cross roller cutters, re-

a bithead spectively, and arms extending upwardly from the outer ends ofsaid pins for supporting the same, said arms having their inner surfacesadjacent their lower ends extending upwardly and inwardly substantiallyat right angles to said cross cutter pins, whereby thecross sectionareas of said arms will increase upwardly.

7. In a cutter and bearing assembly for a roller bit, a bridge havingdownwardly and inwardly inclined spindles adjacent its opposite ends,side cutters rotatably mounted on said spin- .dles, cross cutter pinsextending. upwardly and outwardly from the intermediate portions of saidbridge; cross cutters rotatably mounted on said pins, and securing armsextending upwardly from the outer ends of said spindles and said crosscutter pins respectively for securing said assembly to JOE! 1". SHAW.

